It is the fourth of the Fuji Five Lakes in terms of surface area, and second deepest, with a maximum water depth of 71.1 metres (233 ft).

[2] The remnants of the lava flow are now under the Aokigahara Jukai Forest, and there is evidence to indicate that these three lakes remain connected by underground waterways.

[3] Saiko has no natural drainage, but an artificial channel now connects it to Lake Kawaguchi.

As with the other Fuji Five Lakes, the area is a popular resort, with many lakeside hotels, windsurfing facilities, camp sites, and excursion boats.

Japanese white crucian carp, wakasagi and Kunimasu were introduced to the lake in the Meiji period, and sports fishing is also popular.